Anyone use Nike + ipod?

Does anyone here use Nike + ipod? I was thinking of getting one and I know that you can do 'challenges' with other people and was wondeirng if anyone here has ever done that? Would anyone be intrested? Like I said I dont have one yet but I want to get one to help motivate me to walk more after my surgery (gadgets tend to make me more excited about my wokrouts) :)

I have one and I love it. It really helps to keep track of my runs and being in challenges with people is so much fun.